#define TRUE 1
#define FLASE 0
#define INVALID -1
#define NULL 0
#define total_instruction 320
#define total_vp 32
#define clear_period 50

typedef struct {
	int pn;
	int pfn;
	int counter;
	int time;
}pl_type;

pl_type pl[total_vp];

typedef struct pfc_struct{
	int pn;
	int pfn;
	struct pfc_struct *next;
}pfc_type;

pfc_type pfc[total_vp], *freepf_head, *busypf_head, *busypf_tail;
int diseffect, a[total_instruction];
int page[total_instruction], offset[total_instruction];
int initialize(int);
int FIFO(int);
int LRU(int);
int LFU(int);
int NUR(int);
int OPT(int);

int main() {
	int s, i, j;
	srand(10 * getpid());
	s = (float)319 * rand( ) / 32767 / 32767 / 2 + 1;
	for(i = 0; i < total_instruction; i += 4) {
		if( s < 0 || s > 319 ) {
			printf("When i==%d,Error,s==%d\n", i, s);
			exit(0);
		}
		a[i] = s;
		a[i + 1] = a[i] + 1;
		a[i + 2] = (float)a[i] * rand( ) / 32767 / 32767 / 2;
		a[i + 3] = a[i + 2] + 1;
		s = (float)(318 - a[i + 2]) * rand( ) / 32767 / 32767 / 2 + a[ i + 2] + 2;
		if((a[i + 2] > 318) || (s > 319))
			printf("a[%d+2],a number which is :%d and s==%d\n", i, a[i + 2], s);
	}
	for (i = 0; i < total_instruction; i++) {
		page[i] = a[i] / 10;
		offset[i] = a[i] % 10;
	}
	for (i=4;i<=32;i++){
		printf("---%2d page frames ---\n", i);
		OPT(i);
	}
	return 0;
}

int initialize(int total_pf) {
	int i;
	diseffect = 0;
	for(i = 0; i < total_vp; i++) {
		pl[i].pfn = INVALID;
		pl[i].counter = 0;
		pl[i].time = -1;
	}
	for(i = 0; i < total_pf - 1; i++) {
		pfc[i].next = &pfc[i + 1];
		pfc[i].pfn = i;
	}
	pfc[total_pf - 1].next = NULL;
	pfc[total_pf - 1].pfn = total_pf - 1;
	freepf_head = &pfc[0];
	return 0;
}

int OPT(int total_pf) {
    int i, j, max, maxpage, d, dist[total_vp];
    pfc_type *t;
    initialize(total_pf);
    for(i = 0; i < total_instruction; i++) {
        if(pl[page[i]].pfn == INVALID) {
            diseffect++;
            if(freepf_head == NULL) {
                for(j = 0; j < total_vp; j++) {
                    if(pl[j].pfn != INVALID)
                        dist[j] = 32767;
                    else
                        dist[j] = 0;
                }
                for(j = 0; j < total_vp; j++) {
                    if((pl[j].pfn != INVALID) && (dist[j] == 32767)) {
                        dist[j] = j;
                    }
                }
                max = 0;
                for(j = 0; j < total_vp; j++)
                    if(max < dist[j]) {
                        max = dist[j];
                        maxpage = j;
                    }
                freepf_head = &pfc[pl[maxpage].pfn];
                freepf_head->next = NULL;
                pl[maxpage].pfn = INVALID;
            }
            pl[page[i]].pfn = freepf_head->pfn;
            freepf_head = freepf_head->next;
        }
    }
    printf("OPT:%6.4f\n", 1 - (float)diseffect / 320);
    return 0;
}
